The instant invention pertains to white, dyed, dipped, unscented and/or scented candle wax which is effectively stabilized against discoloration and fading by the incorporation therein of an imidazolidine in combination with a UV absorber and/or an antioxidant.
Candles have been known for many centuries going back to the eighth century B.C. The nature of candles is described in Ullmann""s Encyclopedia of Industrial Chemistry, Volume A5 at pages 29-30 where it is seen that candles are made from paraffin, beeswax and stearin as basic materials, and where a host of additives may also be present.
It is not surprising that with candles and wax becoming increasingly more important attention was paid as to how to stabilize the said materials. At the National Candle Association Meeting in Houston, 1994, R. van der Vennet presented a paper on xe2x80x9cAntioxidants in Waxxe2x80x94Replacement of BHTxe2x80x9d touting the use of Vitamin E (tocopherol) as an antioxidant to prevent the yellowing of wax when oxidized. WO 94/13736 describes the same invention.
EP 359,488 A3 and EP 133,964 B1 describe stabilized waxes used in cosmetics where the waxes are the same or similar to those used in candles.
EP 5,922 A1 describes lip cosmetics where the waxes are useful in lipsticks and are related to those useful in candles.
U.S. Pat. No. 5,879,694 describes in detail transparent gel candles both in composition and structure. The use of BHT as an antioxidant is mentioned.
At the National Candle Association Technical Meeting on Apr. 16, 1998, F. A. Ballentine et al., presented a paper entitled xe2x80x9cInhibiting Color Fading of Dyed Candles with CYASORB(copyright) Light Absorbersxe2x80x9d in which the general theories of thermal oxidation and photodegradation are discussed along with data on the effect of light absorbers on color stability of dyed candle waxes. The light absorbers compared are 4-octyloxy-2-hydroxy-benzophenone UV-531; 4-methoxy-2-hydroxybenzophenone UV-9; 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole UV-5365; 2-(2-hydroxy-5-tert-octylphenyl-2H-benzotriazole UV-5411 and 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole UV-2337).
U.S. Pat. No. 5,964,905 teaches dyed and scented candle gels containing triblock copolymers and a hydrocarbon oil of high flash point. This reference teaches that a light (UV) absorber may be used to improve the shelf stability of the candle color when exposed to visible or ultraviolet light. Two preferred absorbers are ethylhexyl p-methoxycinnamate (PARSOL(copyright) MCX, Roche) and 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole (CYASORB(copyright) 5411, Cytec).
Imidazolidines have been known as stabilizers for various substrates. British Patent No. 1,145,470 teaches the stabilization of polyolefins using alkylated 4-oxoimidazolidine-1-oxides such as 2,2,5,5-tetramethyl-4-oxoimidazolidine-1-oxide.
U.S. Pat. No. 4,448,969 discloses the use of cyclic ether or carbonate alkylation products of 2,2,5,5-tetramethylimidazolidin-4-one for the stabilization of synthetic polymers, particularly polyolefins.
U.S. Pat. Nos. 4,804,717 and 4,895,901 teach that polymeric hindered amine light stabilizers are useful for the stabilization of olefin, styrene and acrylate polymers which contain a minor amount of a pendant moiety derived from 3-hydroxy-2,2,5,5-tetramethylimidazolidine-4-one.
European Patent Specification 313,941 B1 describes the stabilization of photochromic dye compositions using 1-oxyl-2,2,5,5-tetramethylimidazolidin-4-one.
WO 00/22037 teaches the stabilization of solid, shaped and colored wax articles, including candles, using a malonate UV absorber which may optionally contain a hindered amine moiety as part of the malonate compound structure. The wax articles are dyed with a variety of oil soluble dyes and pigments. The samples protected by dimethyl p-methoxy-benzylidinemalonate exhibited better resistance to discoloration that did samples stabilized with selected benzotriazole or benzophenone UV absorbers.
Japanese Hei 3-278554 teaches that wax crayons (drawing materials) colored by organic pigments can be stabilized by a hindered amine and/or benzotriazole.
U.S. Pat. No. 6,020,491 teaches the use of monomeric and polymeric cyclic amine and N-halamine compounds as biocides and disinfectants for a host of substrates. Some of the structures include a substituted 2,2,5,5-tetramethylimidazolidine moiety in a pendant group.
WO 98/30601 describes a method of controlling polymer molecular weight and polymer structure by living free radical polymerization where nitroxide and alkoxyamine containing a 2,2,5,5-tetramethylimidazolidine moiety are employed.
WO 99/61396 teaches the method of stabilizing unsaturated organic polymers using a host of polymerization inhibitors based on the alkylated 2,2,5,5-tetramethyl-imidazolidine compounds.
In respect to wax stabilization, the use of selected hindered amines and/or benzotriazole UV absorbers is also known in the prior art as seen in U.S. Pat. Nos. 3,530,084; 4,379,721; 4,616,051 and 5,964,905 and in copending applications Ser. Nos. 09/495,495, 09/495,496 and 09/741,583.
None of these references teach the superior performance provided when the imidazolidine compounds are used in conjunction with a UV absorber and/or antioxidant to stabilize candle wax.
The object of the invention is to provide for a white and unscented; white and scented; dyed and unscented; dyed and scented; dipped and unscented; or dipped and scented candle wax stabilized by a combination of an imidazolidine compound with a UV absorber and/or antioxidant.
The instant invention pertains to a composition which comprises
(a) candle wax which is white and unscented; white and scented; dyed and unscented; dyed and scented; dipped and unscented; or dipped and scented, and
(b) an effective stabilizing amount of a combination of
(i) an imidazolidine compound containing a moiety of generic formula I 
(ii) a UV absorber or an antioxidant, or a UV absorber and an antioxidant
wherein the ratio by weight of (i) to (ii) is from 10:1 to 1:10.
In another embodiment of the instant invention, the imidiazolidine compound of component (b)(i) is a compound of formula Ia 
where
R1 and R2 are independently alkyl of 1 to 8 carbon atoms, or R1 and R2 together are tetramethylene, pentamethylene or pentamethylene substituted by methyl; and
R3 and R4 are independently hydrogen, oxyl, hydroxyl, aralkyl of 7 to 15 carbon atoms, alkoxy of 1 to 24 carbon atoms, alkyl of 1 to 42 carbon atoms, said alkyl substituted by one or two hydroxyl groups, said alkyl substituted by alkylcarbonyloxy of 2 to 18 carbon atoms, or said alkyl interrupted by one to twenty oxygen atoms and substituted by one hydroxyl, by alkylcarbonyloxy of 2 to 18 carbon atoms or by 4-hydroxy-3,5-di-tert-butylbenzoyloxy.
In another embodiment of the invention R1 and R2 are each methyl, or R1 and R2 together are pentamethylene.
Specific imidazolidine compounds of formula I or Ia which are useful in the instant invention include
(a) 2,2-pentamethylene-5,5-pentamethylene-imidazolidin-4-one;
(b) 2,2-pentamethylene-5,5-pentamethylene-imidazolidin-4-one-1-oxyl;
(c) 2,2,5,5-tetramethyl-4-oxoimidazoline-1-oxyl;
(d) 2,5-dimethyl-2,5-diisobutyl-4-oxoimidazoline-1-oxyl;
(e) (2,2,6,6-tetramethylpiperidine-1-oxyl)-4-spiro-2xe2x80x2-(4-oxoimidiazoline-1-oxyl)-5xe2x80x2-spiro-4-(2,2,6,6-tetramethylpiperidine-1-oxyl);
(f) 2,5-dimethyl-2,5-diethyl-4-oxoimidazoline-1-oxyl;
(g) 2,2-[(1-methyl)-1,5-pentanediyl]-5,5-[(1-methyl)-1,5-pentanediyl]-imidazo-lidin-4-one-1-oxyl;
(h) 2,2,5,5-tetramethyl-1-(2-hydroxyethyl)-imidazolin-4-one;
(i) bis-[2-(2,2,5,5-tetramethyl-4-oxo-imidazolin-1-yl)ethyl] sebacate;
(j) 2,2,5,5-tetramethyl-1-methyl-3-(2-hydroxyethyl)-imidazolin-4-one;
(k) 2,2,5,5-tetramethyl-1-methyl-3-[H(OCH2CH2)x]-imidazolin-4-one where x is 2 to 21;
(l) 2,2,5,5-tetramethyl-1-methyl-3-[heptadecylcarbonyl(OCH2CH2)x]-imidazolin-4-one where x is 2 to 21;
(m) 2,2,5,5-tetramethyl-1-methyl-3-[4-hydroxy-3,5-di-tert-butylbenzoyl-(OCH2CH2)x]-imidazolin-4-one where x is 2 to 21;
(n) 2,2,5,5-tetramethyl-1-methyl-3-[2-(heptadecylcarbonyloxyethyl]-imidazolin-4-one;
(o) 2,2,5,5-tetramethyl-3-methyl-1-[2-(heptadecylcarbonyloxyethyl]-imidazolin-4-one;
(p) the transesterification product of a 1:1 methyl methacrylate:ethyl acrylate copolymer with 3-hydroxyethyl-2,2,5,5-tetramethylimidazolidin-4-one; or
(q) the transesterification product of a 2:1 methyl methacrylate:ethyl acrylate copolymer with 3-hydroxyethyl-2,2,5,5-tetramethylimidazolidin-4-one.
Another embodiment of the instant invention is where the imidazoline compound of component (b)(i) is 2,2-pentamethylene-5,5-pentamethylene-imidazolidin-4-one.
In another embodiment of the invention, the ratio by weight of (i) to (ii) is from 4:1 to 1:4.
Another embodiment of the invention is where the ratio by weight of (i) to (ii) is from 2:1 to 1:2.
In still another embodiment of the invention, the effective amount of the UV absorber plus the imidazoline compound in the candle wax is 0.01 to 10% by weight based on the wax.
Another embodiment of the invention is where the effective amount of the UV absorber plus imidazolidine in the candle wax is 0.1 to 2% by weight based on the wax.
Another embodiments of the invention is where the effective amount of the UV absorber plus imidazolidine in the candle wax is 0.1 to 0.5% by weight based on the wax.
The UV absorber of component (ii) is a benzotriazole, a benzophenone, an xcex1-cyanoacrylate, an oxanilide, an s-triazine, a cinnamate, a malonate, a benzoate or a salicylate, or a mixture thereof.
In another embodiment of the invention, the UV absorber is a benzotriazole, a benzophenone or an s-triazine.
Examples of the UV absorbers useful in the instant invention are
(a) 4-octyloxy-2-hydroxybenzophenone;
(b) 4-methoxy-2-hydroxybenzophenone;
(c) 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole;
(d) 2-(2-hydroxy-5-tert-octylphenyl-2H-benzotriazole;
(e) 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole;
(f) octyl 3-(benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(g) 2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(h) 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole;
(i) 5-chloro-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(j) 5-chloro-2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotriazole;
(k) 2-(2-hydroxy-3-sec-butyl-5-tert-butylphenyl)-2H-benzotriazole;
(l) 2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole;
(m) 2-(2-hydroxy-3-dodecyl-5-methylphenyl)-2H-benzotriazole;
(n) 2-[2-hydroxy-3,5-di(xcex1,xcex1-dimethylbenzyl)phenyl]-2H-benzotriazole;
(o) 2-[2-hydroxy-3-(xcex1,xcex1-dimethylbenzyl)-5-tert-octylphenyl]-2H-benzotriazole;
(p) 2-{2-hydroxy-3-tert-butyl-5-[2-(omega-hydroxy-octa(ethyleneoxy)carbonyl)-ethyl]phenyl}-2H-benzotriazole; and
(q) 2-{2-hydroxy-3-tert-butyl-5-[2-(octyloxy)carbonyl)ethyl]phenyl}-2H-benzotriazole.
(r) 2-ethylhexyl p-methoxycinnamate;
(s) 4-methoxy-2,2xe2x80x2-dihydroxybenzophenone;
(t) 4,4xe2x80x2dimethoxy-2,2xe2x80x2-dihydroxybenzophenone;
(u) 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-octyloxyphenyl)-s-triazine;
(v) 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-s-triazine;
(w) 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-do-/tri-decyloxy-2-hydroxy-propoxy)phenyl]-s-triazine;
(x) 2,4-bis(2,4-dimethylphenyl)-6-[2-hydroxy-4-(3-do-/tri-decyloxy-2-hydroxy-propoxy)-5-xcex1-cumylphenyl]-s-triazine;
(y) reaction product of 2,4,6-tris(2,4-dihydroxyphenyl)-s-triazine with octyl xcex1-haloacetate; or
(z) the mixture of 3,3;3,5;5,5-methylene-bis[2,4-bis(2,4-dimethyl-phenyl)]-6-[2-hydroxy-4-(3-butyloxy-2-hydroxypropoxyphenyl)]-s-triazine.
Still other examples of UV absorbers useful in the instant invention are
(a) 4-octyloxy-2-hydroxybenzophenone;
(b) 4-methoxy-2-hydroxybenzophenone;
(d) 2-(2-hydroxy-5-tert-octylphenyl-2H-benzotriazole;
(o) 2-[2-hydroxy-3-(xcex1,xcex1-dimethylbenzyl)-5-tert-octylphenyl]-2H-benzotriazole;
(p) 2-{2-hydroxy-3-tert-butyl-5-[2-(omega-hydroxy-octa(ethyleneoxy)carbonyl)-ethyl]phenyl}-2H-benzotriazole;
(q) 2-{2-hydroxy-3-tert-butyl-5-[2-(octyloxy)carbonyl)ethyl]phenyl}-2H-benzotriazole;
(y) reaction product of 2,4,6-tris(2,4-dihydroxyphenyl)-s-triazine with octyl xcex1-haloacetate; or
(z) the mixture of 3,3;3,5;5,5-methylene-bis[2,4-bis(2,4-dimethyl-phenyl)]-6-[2-hydroxy-4-(3-butyloxy-2-hydroxypropoxyphenyl)]-s-triazine.
Another embodiment of the instant invention involves a composition wherein the antioxidant is a phenolic antioxidant, phosphite, nitrone, amine oxide or hydroxylamine, or mixture thereof.
Examples of the above-embodiment are wherein the effective amount of UV absorber in combination with the imidazolidine compound and an antioxidant is 0.01 to 10% by weight based on the wax.
Another embodiment is where the effective amount of UV absorber in combination with the imidazolidine and an antioxidant is 0.1 to 2% by weight based on the wax.
Still another embodiment is where the effective amount of UV absorber in combination with the imidazolidine and an antioxidant is 0.1 to 0.5% by weight based on the wax.
Examples of the antioxidants useful in this invention are
n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate,
neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinammate),
di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate,
1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,
thiodiethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,
3,6-dioxaoctamethylene bis(3-methyl-5-tert-butyl-4-hydroxyhydrocinnamate),
2,6-di-tert-butyl-p-cresol,
2,2xe2x80x2-ethylidene-bis(4,6-di-tert-butylphenol),
1,3,5-tris(2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl) isocyanurate,
1,1,3,-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,
1,3,5-tris[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)ethyl] isocyanurate,
3,5-di-(3,5-di-tert-butyl-4-hydroxybenzyl)mesitol,
hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),
1-(3,5-di-tert-butyl-4-hydroxyanilino)-3,5-di(octylthio)-s-triazine,
N,Nxe2x80x2-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide),
calcium bis(ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate),
ethylene bis[3,3-di(3-tert-butyl-4-hydroxyphenyl)butyrate],
octyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate,
bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazide, N,Nxe2x80x2-bis[2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)-ethyl]oxamide,
N,N-di-(C12-C24alkyl)-N-methyl-amine oxide, of
N,N-dialkylhydroxylamine prepared from di(hydrogenated tallow)amine by direct oxidation.
Still other embodiments of antioxidants useful in the instant invention are
neopentanetetrayl tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate),
n-octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate,
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,
1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,
2,6-di-tert-butyl-p-cresol, or
2,2xe2x80x2-ethylidene-bis(4,6-di-tert-butylphenol).
It should be noted that candles contain a host of various components. The base materials may be made up of the following:
paraffin wax,
natural oils,
polyamide plus fatty acid/ester,
fatty acids such as stearin,
opacifiers,
beeswax,
glycerides plus oxidized wax,
alcohols, and
ethylene oligomers.
Candles also contain a number of additives such as the following:
mold release agents,
fragrances,
insect repellants or insecticides,
hardeners,
crystal modifiers,
clarifiers,
guttering reducers,
colorants,
f.p. control agents,
stretchability improvers,
gelling agents,
extrusion aids, and
vortex reducers.
Each of the various components are meant to control or modify the properties of the candle to insure proper burning, reduce channelling, aid in uniform melting, and the like. The colorants and fragrances obviously are there to provide the proper color, scent or other aesthetic appeal.
Of increasing importance are the transparent gel candles which look like clear glass, but which burn like a classical candle. As is discussed in detail in U.S. Pat. No. 5,879,694, the relevant parts of which are incorporated herein by reference, these gel candles usually contain a copolymer selected from the group consisting of a triblock, radial block, diblock or multiblock copolymer classically made up of at least two thermodynamically incompatible segments containing both hard and soft segments. Typical of such block copolymers is KRATON(copyright) (Shell Chemical Co.) which consists of block segments of styrene monomer units and rubber monomer or comonomer units. The most common structure found in KRATON(copyright) D series is a linear ABA block with styrene-butadiene-styrene (SBS) or styrene-isoprene-styrene (SIS).
The following examples are meant for illustrative purposes only and are not to be construed to limit the instant invention in any manner whatsoever.
Raw Materials
Wax samples are supplied by the Candle-Lite Corporation. These samples contain dyes and fragrances.
The UV absorbers and hindered amine stabilizers are obtained from the Ciba Speciality Chemicals Corporation.
Sample Preparation
The wax samples obtained from the Candle-Lite Corporation already contain a dye and a fragrance (scent). In these cases, the wax is melted and the appropriate stabilizer(s) is (are) added and dissolved in the molten wax. The stabilized wax is then poured into five (5) 44 mm diameter aluminum pans giving five (5) wax disks.
Sample Exposure
Triplicate samples of each disk are exposed under a bank of six (6) cool-white fluorescent lamps (40 watts) or under a bank of six (6) UV lamps having a wavelength of 368 nm with the test samples being twelve (12) inches (30.48 cm) below the lamps.
Dye color fade (or color change) is measured by a Macbeth ColorEye Spectrophotometer with a 6 inch integrating sphere. The conditions are: 10 degree observer; D65 illuminant and 8 degree viewing angle.
Initial color measurements are taken using the above parameters. The L, a and b values are calculated using the CIE system from the reflectance values. YI is calculated from the L, a and b values. Subsequent measurements are taken at specified intervals. Delta L, a, b and YI values are simply the difference between the initial values and the values at each interval. Delta(xcex94) E is calculated as follows:
[(Delta L)2+(Delta a)2+(Delta b)2]xc2xd=Delta E.